1991 735i. I have no manual and I can't find the positive post under the hood. Actually, I think I've found where it's supposed to be, but there's no post there. When I stand on the driver's side, I see something immediately left of the fuse box. Think of it as a cube with the top and two ends missing. About 1" wide, by 2" long by 2" deep. At the bottom center is what appears to be a pair of metal leads folded down. There's superficial damage, and I can imagine that there was once a post rising from one of these downfolded pieces.

Is that it? If so, any suggestions as to how I can go about jump-starting the car?

'the positive terminal is located between the shock tower and the firewall (rear of engine bay) on the drivers side (735i/iL & 750iL) or on the pass side next to the coolant reservoir on the 740i/iL . It should be located under a plastic cover with a "+" symbol embossed on it (sometimes its been removed/missing ). The negative terminal is located on the drivers side shock tower. Look for a hex shaped bolt sticking out of the shock tower'